1. Field of the Invention
The present invention relates to a torch for MIG welding, which is capable of removing spatter deposited on a gas nozzle.
2. Description of the Related Art
According to MIG welding (Metal Inert Gas arc welding), a shielding gas is supplied from the gas nozzle of a torch, and an electrode wire is supplied from the center of a tip disposed axially in the gas nozzle, producing an arc to melt the electrode wire for welding workpieces. MIG welding is more efficient than TIG welding, and is used to weld workpieces of aluminum, copper alloy, soft steel, or the like. The shielding gas comprises an inert gas, such as an argon gas or the like, which prevents the molten metal from becoming oxidized or nitrided during the welding process. Therefore, the shielding gas makes it unnecessary to use a coating material or a flux on the electrode wire.
During the MIG welding process, molten particles tend to be scattered from the pool of molten metal, and deposited as spatter on the tip end or along the inner surface of the gas nozzle, resulting in a reduction in welding efficiency and quality of the welded assembly. For removing welding spatter, there have been proposed a spatter removal device using a rotating brush to remove spatter (see, for example, Japanese Laid-Open Patent Publication No. 61-17377), a spatter removal device that uses a force to press a nozzle to remove spatter (see, for example, Japanese Laid-Open Patent Publication No. 2003-1425), and a spatter removal device that removes spatter with a rotary tool having surface irregularities (see, for example, Japanese Patent No. 3367340).
The spatter removal devices disclosed in Japanese Laid-Open Patent Publication No. 61-17377, Japanese Laid-Open Patent Publication No. 2003-1425 and Japanese Patent No. 3367340 do not involve use of a MIG welding torch. For removing spatter deposited on a gas nozzle, using any of these spatter removal devices, it is necessary to interrupt the MIG welding process, move the torch, and install the torch on the spatter removal device. Kinetic energy is necessary to rotate the brush or the rotary tool, or to press the nozzle, and thus a complex mechanism is required for rotating the brush or the rotary tool, or to press the nozzle.
A MIG welding process may be performed by a torch mounted on the tip of a robot arm. However, a robotic welding process poses a significant burden on the operator, because the operator is required to train the robot how to weld workpieces, in addition to removing spatter.